There is a need in many areas of application in industry, in particular within different process industries, to be able to limit the vacuum in apparatus, containers, treatment vessels, conduits and the like in which a space in the apparatus or equivalent in question is normally under a certain vacuum. Within the pulp and paper industry, for example, there are many points at which apparatus is operating under a certain vacuum. For example, vacuum pumps are used to deaerate pulp suspensions. In this context it is important that the vacuum does not exceed a given value as fibre pulp would otherwise be able to get into the vacuum pump. For this reason, it is customary to arrange vacuum valves in the wall which delimits the space which is under vacuum, with the valve being set so that it opens and allows air into the space if the vacuum exceeds a certain value. In this connection, it is known to use valves of the type described in a general fashion above, with the external force for pressing the valve body against the valve seat, with the counteraction of the force developed by the vacuum, being produced with the aid of a mechanical, coil-shaped spring, whose spring constant can be regulated using a screw, for example. A disadvantage of these known valves is that the spring must be relatively long, resulting, in turn, in the whole valve forming a long protuberance on the apparatus, conduit or equivalent in question. This results in the valve being readily subject to damage due to external action, particularly since the apparatus, conduit or equivalent, and consequently the valve as well, is often located in those environments where there is a high risk of damage.